Thread cutter for sewing machines



' A. F. FIFIELD.

THREAD CUT'IER FOR SEWING MACHINES.

APPLICATION FILED DEC-8,191]- 1,401,973. Patente Jan. 3,1922.

INVENTOR ALBERT F. FIFIELD, OF NEWARK, -NEW JERSEY, ASSIGNOR TO THESINGER MAN U- FACTURING COMPANY, A CORPORATION OF NEW JERSEY. V

THREAD CUTTER FOR SEWING MAGHINESJ Specification of Letters Patent.

Patented Jan. 3,1922.

Application filed December 8', 1917.. Serial No. 206,197. i

To all whom it may concern:

Be it known that I, ALBERT F. FIFIELD, a citizen 1 of the United States,residing 'at Newark, in'the county of Essex and State of New Jerseyyhaveinvented certain new and useful Improvements in'Thread Cutters forSewing Machines, of which the'following is a specification, referencebeing had therein to the accompanying drawings.

This invention relates to attachments for sewing machines. for cuttingthe thread at the end of a stitching operation.

An object of this invention is to provide new and improved means .forcutting'the thread close to the under side of the work. A further objectof the invention isto provide new and improved means for. pullin offthread from the supply so that the thread end will not be drawn. throughthe needleeye when stitching is resumed. And a: still further object ofthe inventionis'to provide common means for actuating the cutter andpull-off so that the latter mustfunction before'the former. It is alsoan aim of this invention to arrange and locate the pull-01f andthread-cutter out of the operatives way and out of her line of .visionininspecting the work around the presser-foot. And finally it is anobject ofthis invention to attain the ends above stated with simpleinexpensive means and without encumbering the stitch-forming mechanismwith the weight of the additional parts.

Other objects of the invention will appear in the description of theaccompanying drawings, in which Fig. 1 is a side elevation of a machineequipped with the invention. Fig. 2 is a cross-sectionadjacent thestitching point showing in solid lines the normal position of thecutting blade and in dotted lines the position the cutting blade assumesto enter the loops of thread on a' looper before a severing operation.Fig.3 is a cross-section adjacent the looper operating cam lookingtoward the stitching point. Fig. 4 is a perspective of the cuttingblades and thread previous to'a severing operation and Fig. 5 is abottomplan vview of the looper-carrier or clamp] I The invention asillustrated is embodied in a twin-needle and looper chain-stitch ma-,-chine in which the needles 1 are carried by a needle-bar 2 reciprocatingin. a head 3 on an overhanging arm 4 in which is j ournaled theneedle-bar operating shaft 5 driven by ajpitman 6 linking a crank-arm 7on the shaft 5 w1th an eccentric (not shown) on the main-driving shaft 9which is located beneath the work-support or cloth-plate 1O inlaid 1nwhich is'the usual throat-plate 11. The t-wo loopers 12 are supported ina carrier Fig.7 5 having a pair of sockets 14 receiving the shanks ofthe loopers and ashght-space 15 separates a pair of clamping arms 16, 17into one of which, 16. is threaded a screw 18 loosely passing-throughthe other arm, 17. A wall 14, preferably rigid, separates the spacedsockets. The space or saw-cut l5-is of such width and extent that itcommunicates with both the sockets 14 and permits a tight gripping orblnding of the looper-shanks when the screw 18 is'tightened. Theloopersare moved endwise through mechanism which will now be described. Thelooper-carrier or clamp 13 is secured in any suitable manner to a rod 19passing through a bushing 20 supported in a part 21 of the base 22 ofthe frame of the machine. Atthe opposite end the rod 19 car ries acrank-like arm 23 connected by a link 24 to an arm 25' on the looperactuating shaft 25 which is journaled below and in line with theneedle-paths and which carries centrally of the length of the machine anarm 26 having a roller or follower 27 extending into a cam-groove 28 inthe face of a disk '29 on the main-shaft 9 of-the machine. I Thefeedingmechanism is not shown as it forms no-part of" the present invention andit is to be understood that any suitable formv of feeding -mechanism maybe employed. i

The thread-controlling mechanism comprises essentially a take-upindicated generally by the numeral 30 which also may be of any suitableconstruction and an intermittent tension 31 actuated automatically from.a cam 32 on the needle-bar operating shaft 5 in a manner well known andsubstantially the same as that disclosed in a patent to one Hemleb, No.1,254,225, dated January 22, 1918. v Betweencthe intermittent tension 31and the needlesa pair of thread-eyes 33 are locatedspaced apart a slightdistance on the overhanging arm. Intermediate these thread-eyes 33 athread-engaging member 34 is arrangedto swing from its normal positionshown in Fig. 1 down below the line of the eyelets 33. Thisthread-engaging member is preferably formed on the end of an' arm 35fulcrumed at 36 on the overhanging arm and connected by a bent link 37to a cranlrarm 38 on the rock-shaft 39 Supported by spaced brackets 40secured to the base 22 of the frame. i

The thread-cutter is located adjacentthe loopers 12 and the throatlate11 of both of which it is supported in ependently. The thread-cuttingblade 41 in the embodiment shown resembles a split spear head and itisprovided with two cutting edges indicated by the numeral 42, as in thisembodiment it is usedwith a twin-needle and looper machine and a cuttingedge is provided for each loop. It is, however, tov benoted that-eachcuttingedgeoperates independently of the other and this edge isduplicated in the illustration merely because there are two loops shownanda cutting edge is desirable for each loop. Obviously if thisthread-cutter were installed in a machine with a single loop but onecutting edge would be necessary. The blade 41 is secured to a carrier 43con.- veniently pivoted or fulcrumed upon a projecting portion of thebushing 20 and held against lateral movement by an apertured plate orclip 43, Figs. land 2, secured in any suitable manner to the portion21of the base and thereby the cutting blades are constrained to move in afixed path concentric, or substantially so, with the path of the loopers12. The'blades 41 are actuated from the rock-shaft 39 by the arm 44connected by a link 45 to the blade-carrier 43. Normally the cuttingblades are held in an out of the way position, as shown'in solid linesFig. 2, by the spring 46 coiled about the shaft 39 and tensionedbyfixedly anchoring one end in any'suitable manner andsecuring the otherend in the collar 47 adjustable about the shaft 39. One of the brackets40 afiords a fixed abutmentin the path of the stop or arm 49 on theshaft 39 and determines the normal and inefiective position of the blade41 as well as of the thread-engaging member 34. 3

The thread-outters 42 and the thread-ed gaging member 34 cannot beoperated when the needle is in the path ofthe cutter and when theintermittent or automatic tension is closed by reason of the provisionof an: other arm 50 on the rock-shaft 39 carrying a friction-roller 51and arranged with reference to the periphery of the looper-actuating camor disk 29 so that neither a cutting nor drawing 011. of thread can beaccomplished unless a notch or recess 52 in the disk 29 is opposite: theroller 51. Still another arm 53 is clamped to thero'ck-shaft 39 andextends forwardly toward the front of the machine where it alfords aconvenient 7 finger-lever for turning the rock-shaftand ting-blade 41":areof such extent that the thereby simultaneously moving thethreadcutting blades 41 and threadengaging member34.

, When the machine has been brought to rest after a stitching operationthe operator "0 may lift the finger-lever 53 which will pull thethread-engaging member 34 down from a line between the eyelets 33 todraw off thread from the supply and simultaneously advance the cuttingblades from the solid line to the dotted line positions shown in Fig. 2.When the operative releases the finger-lever 53 the spring 46 will turnor tend to turn-the rock-shaft 39 in a counterclockwise direction,viewing Fig. 3, and thereby simultaneously restore or tend to restorethe thread-engaging member 34 to the position shown in Fig. 2 and thecutting blades41 from the dotted line position shown in Fig. 2 to thesolid line position shown therein thus cutting the thread. The cuttingedges 42 preferably are made only moderately sharp and need notbe keen.The work-limb of the needle-loop. caught by the barbed edge will bedragged rearwardly with the cutter in its retracting movement from thedotted line to thesolid line position shown in Fig.2. And owing tothesimultaneous slacking or giving up of the thread by the member 34 thereis no cutting or severing of the thread until the blade nears the solidline position shown in Fig. 2 when the giving up of thread by the member34 will have been completed and when the thread is taut between itsanchored ends, i. e. between the work: and the supply. Thus the cuttingblade performs the dual functions of pulling a predetermined quantity ofthread (measured ofi' by'the member 34) through the eye of the'needl'eto the under side of the work and of severing itwith the severed workend of the thread about 4 to 4;" in length. Preferably themovements ofthe thread-engaging member 34 and of the cutlength of thread running tothe needle will be just long enough to bring the severed end to thesurface of the work when stitching is resumed. Inasmuch as thefinger-lever 53 cannot be lifted unless the recess 52 is oppo- 1 15 sitethe roller 51 and because the recess 52 occupies a position opposite theroller 51 only when the needle is in an elevated position', theoperative cannot either intentionally or unintentionally advance thecutting 120 blades 41 across the needle-path when the needles are downand in the way.

-While I have described the invention as it has been embodied in anactual construction, it is to be distinctly understood thatthe invention is not limited to the precise details disclosed and that variouschanges and modifications may be made without departing from theunderlying principles of the invention.

anonevs Havingthus. set forth the nature of the invention, what-I claimherein is v 1. In asewing machine having st-itchforming mechanismincluding a needle and looper, a. thread cutter having a blade'fulcrumedcoaxially with the looper and movable independently thereof, and manualmeans for operating said blade. 7

2. In a sewing machine having stitchforming mechanism including a needleand looper, a cloth-plate, amain driving-shaft located beneath saidcloth-plate, means for actuating said needle and looper from said maindriving shaft, a threadscutter having a blade fulcrumedon'an axiscoincident with that of the main shaft and movable independently ofthe-looper, and manual means for operating said blade.

3. In a sewing machine having stitchforming mechanism including a needleand looper, a work-suppprt, a thread-cutting blade fulcrumed on a fixedpart of the machine, manual means formoving said blade aboutitsfulcriunincluding a plural-armed rock-shaft located belowthe-work-support, amain shaft "below the work-support, mechanism foroperating said looper from said main-shaft ineluding a movable elementalso located below, thework-supportinterposed in the path of'one'of thearms on the rock-shaft and shaped to" permit movement of said one armand advanceof the cutting blade across theneedle-path only when theneedle is out-of the way.

4:. In a sewing machine having stitch forming mechanism including aneedle, a

throat-plate, thread-cutting and pull-off mechanism including a bladeand a bladecarrier pivotally supported beneath the throat-plate on arelatively stationary part of the machine, means for swinging said bladeacross the needle-path to first pull thread beneath the work and thensever the same, including an arm accessibly presented at the front ofthe machine and an actuating arm, means connecting said actuating arm tothe blade-carrier, a spring for normally holplling said cutting bladeout of the needles pat 5. In a sewing machine having stitchformingmechanism including a needle, a work-support, a thread-cutter comprisinga cutting knife adapted to enter a needlethread loop movable beneath thework support, means located between the needle eye and the supply formeasuring olf thread, and means for actuating said measuring off meansand subsequently pulling the thread measured ofi beneath the work andsevering it with the cutter-blade to furnish thread for the first stitchon resuming operation of the stitch-forming mechanism.

6. In a sewing machine having stitchforming mechanism including aneedle, a work-support, a presser-foot, a thread-cutter comprising I amovable knife-blade only shaped to enter, spread and position aneedle-thread loop by movement in one direction and to sever the threadby movement .in the opposite direction and located entirely beneath thework-support, means located away from" the needle and permittinginspection of the work around the presserfoot'for drawing off-threadfrom the supply, and means for actuating said drawing off means andsaidblade.

- 7. In asewing machine having stitchform ingmechanism including aneedle and looper, a work-support, a take-up, an inter mittenttension'device supported-on a fixed part of the machine away fromthe'needle, athread-cutter having a 'cuttingknife movable beneath thework-support, means located between the needle and the intermittenttensiondevice for drawing off thread from the supply, manual means foractuating the drawing off means and the blade and means permittingoperation of said manual means only when the tension is released. r

8. In a sewing machine having-stitchformingmechanism including a, needleand loopeiya work-support, a thread-cutter having a movable bladelocatedbeneath "the worksupport, an intermittent tension device locatedabove the work-support and remote from theneedle,- a thread-engagingmember located between-the needle and the intermittent i-tension,'fixe'd thread-eyes on opposite sides of said thread-engaging member,and means for moving said threadengagingmember'to draw off thread fromthe supply and for moving said blade to pull and cut the thread after ithas been drawn ofi' including a shaft located beneath the work-supportand provided with a plurality of arms and also including a rotary stopgoverning one of the arms carried by said shaft for'preventing breakingof the needle whenit is below the work-support.

9. In a sewing machine having stitchforming mechanism including a needleand looper, a throat-plate, thread-cutting mechanism having a bladelocated between the looper and the throat-plate and sup-portedindependently of both, a thread gripping device and means for moving theblade endwise in a path concentric with that of the looper to first pullthread beneath the throat-plate and then to cut thethread.

10. In a sewing machine having a stitchforming mechanism including aneedle and looper, a work-support, means above the work-support andoperable when the machine is at rest for measuring off thread from thesupply, and a single means below the work-support for pulling thequantity of thread measured off to the under side of the work and thensevering it.

11. In a twin-needle sewing machine having a work-support and :suitableunderthread handling mechanism arranged therebeneath,.- a threadsevering mechanism includin .a cutting member having a split spear-saped head and provided with relatively sharp edges on the base-portionof the head whereby separate needle-threads may be severed.

12; In a sewingmachine having a worksupport, -1Il combinatlon, twinneedles and loopers cooperatively arranged on opposite sides of thework-support and having afixed path of movement clear of the loopers andintermediate the; loopers and the worksupport, said thread severingmember having a split spear-shaped head provided with cutting edges forsevering each of the needle-threads while it is looped about the looper.i 1 v 13. In a, sewing machine having stitch forming mechanismincludinga needle and looper, thread-cutting means pivoted substantially,coaxially with the looper and mounted so as to be movable independentlythereof, and means for operating said thread-cutting means. 7 r a 4 L14. In a sewing machine having stitchforming mechanism including aneedle, a single means adapted upon operation thereof to draw alength'bf thread through the eye of the needle and subsequently severthe same, means for operating said 'first means, and means between theneedle-eye and the thread supply fordetermining the amount ofthreaddrawn through the needle-eye.

15. In a sewing machine having stitchforming mechanism including aneedle,

means independent of the stitch-forming mechanism adapted to engage theneedle thread loop beneath the work and upon movement thereof drawalength of thread through the needle-eye, said means :also adapted tosubsequently sever the thread, means for operating said first means, andmeans between the needle-eye and the thread supply for determining theamount of thread drawn through the needle-eye. v

16. In a sewing machine having stitchforming mechanism including ,aneedle, thread-severing means including a movable blade, means on theblade adapted upon movement thereof to draw a length of threadthroughthe needle-eye and subseqnently sever said thread, means foroperating the blade, and means between the needleeye and the-threadsupply for-determining the amount of thread drawn through theneedle-eye. a a n g 17. In asewing machine having stitchformingmechanism including a needle and loop-handling means, a work-support,combined thread ;pu11-oif and severing means mounted below thework-support adapted to pull thread from the needle to the underside ofthe work, and later sever the same, means located between the needle andthe supply for measuring ofi thread, and a common actuating means forthethread pull-off and severing means and the measurmg 01f means operatingto first measure oif the thread, then pull the thread measured ofibeneath the work, and then sever the same. In testimony wh name to thisspecification.

c ALBERT F. FIFIELD.

ere'of, I have signed my a

